Eggs and Blood Pressure: An In Depth Analysis

What is high blood pressure?

Blood pressure is measured in two numbers: systolic/diastolic. The systolic blood pressure, the top number, represents the force exerted on artery walls when the heart ejects blood into the aorta. The diastolic pressure, the bottom number, is the pressure when the heart is at rest between ejections [1, 2].

High blood pressure, also known as hypertension, is a medical condition where the force of blood against the walls of the arteries is consistently too high. As defined by the American Heart Association hypertension is characterized by a blood pressure reading of 140/90 mmHg or higher, [4, 5].

High blood pressure is a common condition. It affects about 1 in 3 adults, and often presents for a long time with little to no symptoms. Therefore, it is nicknamed as “the silent death”. Chronic hypertension can lead to serious health problems. Those include cardiovascular disease such as stroke, heart failure, heart attack, other kinds of heart disease and kidney disease [6].

There are two types of hypertension: the primary or essential and the secondary. The secondary is a result of a different already existing disease, like chronic kidney failure. On the other hand, there is no exactly defined cause of essential hypertension. Some of the mechanisms that are probably a part of the development have been identified. They include genetic factors, sodium overload, chronic stress and high sympathetic activity, but also endothelial damage or sleep apnoea.

Anatomy of the egg

An egg, particularly an avian egg, is a multifaceted biomaterial. It contains proteins, lipids, vitamins, minerals, and growth factors required by the developing embryo[7, 8]. It is composed of several beneficial elements, each with its unique properties and potential applications.

The outermost layer of an egg is the eggshell. It is primarily composed of calcium carbonate and has a protective function for the embryo. Because of its structure and sharp hard edges, it is not eaten. An interesting fact is that even when not eaten it found another use. Eggshell is a suitable precursor for the synthesis of hydroxyapatite and calcium phosphate, substances specifically relevant for bone tissue engineering [9].

Beneath the eggshell is the eggshell membrane. This thin on protein build layer has a fibrous structure made of several different biopolymers. Some of them are collagen and hyaluronic acid, which are also found in the human extracellular matrix.[9].

Inside the egg, we find the egg white (albumen) and the egg yolk (vitellus). The egg whites are protein-rich. The egg yolks, on the other hand, are mostly composed of lipids, like cholesterol. But also contain diverse essential nutrients such as proteins, minerals, and vitamins[9].

Nutritional values of eggs

Cocked eggs are a good source of high-quality protein. It is important to remember that despite some beliefs raw eggs have one big drawback. They contain protease inhibitors, which inhibit the protein digesting enzymes in the stomach and intestine. Thus, protein absorption can be impaired as a human is not able to absorb large amounts of big proteins. The boiling process inactivates the majority of these inhibitors. [10]. Organic egg yolks showed the greatest quantities of protein (17.7 g/100 g), potassium (134.7 mg/kg), and copper (0.15 mg/kg). Meanwhile, the yolk of conventional eggs was the most plentiful in Mg (14.6 mg/kg) and Fe (9.05 mg/kg), while the nutraceuticals were in Ca (109.0 mg/kg) and Mn (0.26 mg/kg). [11].

Eggs also contain biologically active components with various health benefits. Among the vitamins are vitamins A, D, E, K, B1, B9 and B12. The amount of two eggs covers around 25% of the daily dose of these vitamins [12]. Thanks to these components and some more, eggs exhibit antibacterial, anti-cancer, anti-inflammatory, and immunomodulatory activities. But also antioxidant and immunomodulatory properties [13, 7, 8]. Another important compound found in the eggs is choline. It is a lipid which helps in the promotion of normal cell activity, liver function, and nutrient transportation throughout the body [14].

Eggs influence on high blood pressure

Eggs are a common part of many diets, this includes hypertensive individuals. However, their impact on high blood pressure is a topic of ongoing research.

A systematic review and meta-analysis of randomized clinical trials by Roya Kolahdouz-Mohammadi et al. found that overall, egg consumption had no significant effect on systolic and diastolic blood pressure in adults [15]. This suggests that for most people, eating eggs does not increase or decrease blood pressure.

However, a study by Thanh-Huyen T Vu et al. has found specific circumstances where egg consumption may affect blood pressure. Interestingly, they found that egg intake was non-linearly associated with systolic and diastolic blood pressure in non-obese women, but not in obese women or men [16].

Another small study by S Y Oh et al. showed that eggs enriched in omega-3 fatty acids have been shown to significantly lower both systolic and diastolic blood pressure [17]. This suggests that the type of egg consumed may play a role in its impact on blood pressure.

Also, a study by Hira Shakoor et al. showed a reduction in blood pressure due to omega-3 egg consumption. This result applied to individuals with metabolic syndrome. However, this is rather an indication of the benefit of omega-3 fatty acids consumption than only due to eggs [18]. Perhaps there can be a link between the eggs and this fatty acid consumption, but this is pure speculation.

It's important to note that these studies have limitations. Definitely, more research is needed to fully understand the relationship between egg consumption and blood pressure. Based on the above-mentioned findings it can be said that in some cases egg consumption can be beneficial. Although mostly, normal egg consumption does not show any influence on high blood pressure. It has to be noted that because eggs contain cholesterol a higher egg consumption should be avoided. high blood cholesterol is a risk factor for hypertension and can worsen the already present condition.